South Korea on Sunday issued its first "grave heat wave" warnings for the southeastern cities of Gyeongsan and Pohang under a new highest-level alert system introduced last month to warn of extreme heat. A pedestrian shields from the sun with a parasol at Dongdaegu Station Plaza in Daegu on July 10 amid a heat wave advisory. (Yonhap) The high-level warnings took effect in the two cities at 10:00 a.m., officials said, after temperatures soared to 39.9 C in Gyeongsan and 37.2 C in Pohang the previous day.Temperatures were again expected to reach 39 degrees C in both cities Sunday.The grave heat wave warnings issued in Gyeongsan and Pohang marked the first since the government adopted the new heat warning system June 1 to alert the public to extreme heat.Under the new alert system, a grave heat wave warning is issued when the daily high is forecast to reach 39 C in areas where the apparent temperature has reached 35 C or higher for at least two consecutive days.Under a grave heat wave warning, people are advised to avoid outdoor activities, stay in the shade and drink plenty of water. (Yonhap)